The invention relates to a heat shield arrangement for a gas turbine combustion chamber with a heat shield having a central throughflow opening for a burner as well as a ridge extending circumferentially at the edge of the throughflow opening. The ridge has a plurality of air blow-by openings for the cool air that is guided to the cold back side of the heat shield facing away from the combustion chamber. Reference is made regarding prior art for example to European Patent document EP 0 471 437 A1 wherein, similarly to this known prior art, the present heat shield is also provided preferably for an annular combustion chamber.
The hot surface of the heat shield must be cooled intensively, for which purpose conventional heat shields have a plurality of cooling air throughput openings through which the cooling air stream directed at the cold back side of the heat shield can pass through the heat shield and thus strike the hot surface of the heat shield, producing a film of cooling air. However, it is not possible under these conditions to sufficiently cool the annular area around the burner throughflow opening, which is subjected to particularly high temperature stress. In addition, the cooling air stream that escapes in the vicinity of the throughflow opening through the gap between a sealing part that receives the burner as well as the heat shield is insufficient for this purpose.
The goal of the invention therefore is to provide measures with whose aid the cooling of the heat shield can be further improved, especially in the vicinity of the burner throughflow opening.
The solution to this problem is characterized by a guide rib provided inside the throughflow opening and aligned essentially parallel to the ridge. The end of the guide rib on the combustion chamber side is bent at an angle in order to deflect the cooling air stream flowing in through the air blow-by openings into the gap between the ridge and the guide rib in the direction of the hot surface of the heat shield. Advantageous embodiments and improvements are described herein.
The invention is described in greater detail with reference to preferred embodiments.